There are many reasons a scuba diver may need to write or draw underwater. For example, a diver may need or wish to communicate with other divers. In addition, the diver may desire to record notes, to aid in gathering reference material, architectural drafting for marine construction, artistic rendering, etc.
Conventionally, most underwater communications are accomplished with hand signals, dive slates and/or electronic instruments. Hand signals can be confusing and are limited in what they can communicate.
Dive slates are limited in the amount that they can record by the size of the slate. When the slate is full, new writing can only be added by erasing all previous work. In urgent situations this erasing time can be inconvenient.
Use of electronic equipment is expensive and often vulnerable in the underwater environment.
Use of multiple pages of waterproof material on a clipboard underwater is awkward because in the marine environment the pages can stick together and are difficult to manipulate especially if the diver is wearing gloves. Multiple page slates also cannot be reused until all previous work has been erased.
Use of a compact note scroll configured with a base on which a pair of rotatably mounted shafts carry an elongated strip of paper, an intermediate portion of which is accessible through a window aperture in a case which covers the base, is proposed in U.S. Pat. No. 4,083,136 (Zelenko). Although Zelenko proposes that the paper can be replaced by coated flexible plastic, so that writing on the strip can be easily erased by rubbing with a cloth or the like, writing on the plastic would readily fade, dissolve or otherwise be removed from the plastic, when under water. The compact note scroll proposed by Zelenko is simply not suitable for the underwater environment.